168 SUMMARY OF CURRENT RESEARCHES RELATING TO 



could be traced in the ovary. The male secondary sexual characters are 

 stimulated to development towards the female type under influence of 

 the parasitism. There is a complete series between unmodified crabs 

 rtud crabs which have almost entirely assumed the female characters. In 

 Eiqmgurus prideauxi a similar development of the female secondary 

 sexual characters in the male was observed. It would appear that the 

 secondary sexual characters are not directly consequent upon the primary, 

 but that both are attributable to some change in the general metabolism, 



Globuligenic Organ in Decapods.* — L. Bruntz gives some notes 

 on the histology of this organ in the crayfish. It is an extremely thin 

 gland, separated from the stomach by a fine layer of connective tissue. 

 It resembles a similar organ in Stomatopoda in consisting of a large 

 number of cellular nodules, without a proper envelope, and lying in 

 the meshes of a connective-fi1)rillar network. They communicate with 

 the blood-vessels through the ophthalmic artery in the crayfish, and the 

 ventral artery in Stomatopods. The young lilood globules do not pass 

 directly into the arterial system, but fall into the hgemocoel, and are 

 transported by the venous blood passing through the tissues. 



Annulata. 



Fertilisation in Serpula crater.f — A. Soulier finds this Polychfet 

 a very convenient subject for the study of fertilisation phenomena. 

 Numerous vacuoles are formed in the erythrophil substance of the 

 nucleolus ; they raise the nucleolar membrane like buds ; they separate 

 from the nucleolus, taking with them cyanophil granulations, which 

 become free in the nucleus, and eventually form vitelline granulations 

 in the cytoplasm. 



The centrosome of the ovum is doulile ; the two daughter-centrosomes 

 are united by a central spindle which soon disappears. The centrosomes 

 penetrate into the nucleus, a second central spindle is formed between 

 them, while mantle-fibres are formed by the rays of the two asters. 

 This first maturation-spindle soon attains complete development, and 

 the first polar body is expelled. The centrosome remaining in the oocyte 

 doubles, and gives rise to the centrosomes of the second maturation - 

 spindle. After the expulsion of the second polar body, the remaining 

 centrosome soon disappears. The nucleolus also vanishes. The presence 

 of a spermatozoon in the cytoplasm hastens the processes of maturation. 



The spermatozoon after entering the ovum is at first intensely 

 stainable, but this character is soon lost. The chromatin divides into 

 small grains which soon become vesicular. The head moves through 

 180°, and soon two centrosomes are seen, derived from the spermocentre 

 and each suiTOunded by an aster. The female pronucleus becomes 

 vesicular, and is gradually reconstituted. The male pronucleus is at the 

 same time reconstituted. The two pronuclei are juxtaposed and fuse. 

 The centrosomes of the first segmentation spindle are derived from the 

 spermocentre. 



* Arch. Zool. Exper., Notes et Revue, xxxv. (1906) No. 3, pp. lix.-lxiv. 

 t Arch. Zool. Exper., v. (1906) No. 3, pp. 403-89 (1 pi. and 31 figs.). 



